The present invention relates to a lubricating unit for rolling element tracks of a linear system, and it relates to a linear system that includes a lubricating unit of this type. The lubricating unit includes a lubricating element housing, in which a receiving space for a lubricating element is formed.
Linear systems in the sense of the present application are rolling element screw drives (e.g., ball screw drives), rolling element bush guides (e.g., ball bush guides), and rolling element-supported profiled rail guides, which are often also referred to as linear guides. An aspect shared by all of these linear systems is that a movable element—which is designed, e.g., as a nut element or carriage element—is supported such that it is movable along a linear guide element, and a longitudinal displacement of the movable element takes place by rolling elements (balls or rollers) rolling between tracks formed on the movable element and the guide element. The rolling bodies move along a closed path in a rolling element circuit with a load channel formed between facing bearing surfaces on the linear guide element and on the movable element, and a return channel that connects the two ends of the load channel and is typically guided by the movable element.
To ensure that the rolling of the rolling elements is satisfactory, the tracks of linear systems of this type must be lubricated with a lubricant (typically a lubricating oil), mainly in the region of the load channel. To enable compensation of lubricant losses that unavoidably occur during operation of a system of this type, it is desired that lubricant be supplied continually during the entire operating period, the lubricant supply ideally remaining consistent for the entire duration of operation and being selected such that its level exactly compensates the lubricant losses. To this end, a lubricating element made of a lubricant-storing material is typically provided on the movable element.
Publication U.S. Pat. No. 5,492,413, for example, discloses a sealing plate for a carriage of a profiled rail guide that is supported such that it is movable along a guide rail. The sealing plate is mounted on both axial ends of the carriage and is bonded with a layer made of a lubricant-saturated, foamed material, which performs the lubricating function. The inner edge of this foamed material layer forms a lubricant delivery lip resting on the guide rail, which is supplied with lubricant from the surrounding regions of the foamed material layer. A further system for lubricating rolling element tracks of a profiled rail guide is made known in JP 5-71143 U. With this system, lubricant-saturated foamed material inserts are inserted in a receiving space of a sealing unit installed on the axial sides of the carriage. The insides of the foamed material inserts are in contact with the rolling element bearing surfaces of the guide rail.
Publication DE 295 04 812 U discloses a ball screw drive with a nut body that includes two circumferential grooves extending parallel to each other on its front end. A retaining ring is held in the first circumferential groove, which secures a ball deflection element, with which rolling balls can be transferred from a helical load channel formed between the inner surface of the nut and the outer surface of a spindle to a return channel formed in the nut and connecting the two axial ends of the load channel. A sealing body is secured in the second circumferential groove located closer to the front end of the nut body, which prevents foreign substances from entering the space formed between the inner surface of the nut and the outer surface of a spindle.